The present invention relates to embodiments of an air compressor head assembly for use in air brake systems for commercial vehicles. Engine driven compressors, such as those used on heavy vehicles, function continuously while the engine is in operation. When a piston inside the compressor compresses the air, a discharge valve in a cylinder head will open and allow the air to pass downstream of the compressor to be treated and stored. This discharge valve may cycle hundreds of times per minute. The surface on which the discharge valve seats, such as a machined portion of a valve plate, will be subjected to the cycling of the discharge valve and may wear quickly. Extreme temperatures caused by air compression may cause thermal expansion between the discharge valve mounting and the valve plate if the discharge valve and valve plate are constructed of different materials, causing a retainer or bridge of the discharge valve to be stressed. Additional sealing and air directing features must be machined into a separate cooling or baffle plate and additional gaskets must be added when the valve plate is dedicated to the mounting of the discharge valve. Each layer of a compressor head assembly provides an opportunity for air leakage and causes additional potential for distortion of the crankcase bore. Therefore, there is a desire for an improved air compressor head assembly.